Hello everyone,

I've been developing a PCIe-based co-processor system using Arria 10 GX Dev Kit and I am having some trouble configuring a proper BAR4 size to address all slaves connected to the PCIe DMA IP. For data transfers from the host to the FPGA, I am using the a Linux DMA driver adapted from the altera_dma driver provided along with the reference design (PCI Express Avalon-MM DMA Reference Design).

My system interconnection is as follows:

PCIe Hard IP (DUT)
|--------------------------------- EMIF(ctrl_avmm_0) 0x0000_0000 - 0x0FFF_FFFF (256 M (28bits)
|--------------------------------- ONCHIP_MEM 0x5000_0000 - 0x0000_001FF (512 (9 bits)
|--------------------------------- CO-PRO 0x1000_0000 - 0x0000_003FF (1024 (10bits)

TOTAL ADDRESSES EXPECTED: 0x1000_0000 + 0x0200 + 0x0400 = 0x10000600

For this configuration, Qsys calculates a 31bit size for BAR4 (0x4000_0000), configure as a 64bit non-prefetchable memory. This length should be enough to cover all EMIF addresses, plus the CO-PRO and ONCHIP. Therefore, from my DMA driver I should be able to read or write single words (iowrite32, ioread32) to any offset from the BAR4 start address, right?

For example, if I wanted to write a 32bit word to the first position on the ONCHIP memory I should:

int onchip_base = 0x50000000;
int data = 0xAB;
__iomem * ptr = pci_ioremap_bar (pdev, 4);
iowrite32(data, ptr + onchip_base);

However, using this strategy I am able to write or read positions on EMIF and CO-PRO (addresses smaller than 0x40000000), but not on the ONCHIP_MEM. I believe the problem is because the base address for the ONCHIP_MEM (0x5000_0000) is greater than the calculated size of the BAR4 (0x40000000). This parameter is not configurable from the the Qsys GUI interface. The reference design documentation says it is automatically calculated when I finish the interconnection.

I would like to know if any of you guys have had this problem and what I am doing wrong. I want to be able to write any position on the design using iowrite32 calls.

Thank you a lot for any help you could give me.